Printing telegraph receiver



April 22, 1952 R. D. SALMON ET AL PRINTING TELEGRAPH RECEIVER Filed Jlily 7, 1948 I3 2/ F G3. 4- TIME I- MILLI$ECONDS (loo wPM) O 20 4O 6O 80 100/20 I40 /60/w20022O hari] 2 3 4 5 stop (77/! I/ I] l 4 km n A. c

2 SHEETS-3S'HEET 1 Inventor R .0 .SALMON F.T.L.TURNE-R Atior ey April 1952 R. D. SALMON ET AL 2,593,489

PRINTING TELEGRAPH RECEIVER Filed July 7, 1948 2 SHEETSSHEET 2 Inventor R D SA L MON F .T.L TURNER Patented Apr. 22, 1952 2,593,483 PRINTING TELEGRAPH RECEIVER Reginald Dennis Salmon and Frederick James Leslie Turner, 'Croydon, England, assignors to Creed and Company Limited, Croydon, Surrey,

England Application July 7, 1948, Serial No. 37,373 In Great Britain July 25, 1947 1 This invention relates to printing telegraph receivers and more particularly to receivers in which storage members are set in accordance with the code elements of the received signal combination and in which the storage members are afterwards caused to act upon translator mechanism whereby a letter or character is printed, or such other function is performed by the machine, as corresponds to the particular signal combination received.

The present invention relates to the selecting 'and'storage mechanism only. In British Patent Specification No. 600,297 it is explained that the degree of tolerance for distorted signals which a printing telegraph receiver can develop depends largely on the moment of inertia of certain moving parts one of which is the armature of the receiving magnet. The armature normally occupies one cf two positions, usually referred to as mark and space and is retained in either one or other position according as to whether the current condition in the winding of the magnet represents a mark or a space signal element. Received signal combinations corresponding to individual letters,

the more tolerance is permissible in the timing of the received signal impulses. In theftype of printing receiver under consideration it is necessary that a succession of stor- "age members should be set into positions corresponding to mark or space determined by successive positions of the receiving relay armature. Printing telegraph systems usually involve the use'jof; a code in which each character or function 'is re'presented by a fixed number of siglimpulses, commonlyfive, each of which may amark or-a space. Thus, for a' five unit code there must be five storage members and the a rmat ure must operate so as to set them one after "another.- As set forth in said British patent one well-known method of accomplishing this involves the use-of a member mounted on the armature of sufficient size to cover the positions "or all the storage members, means being provided whereby an intermediate striking pin is brought into position between the armature and each storage member in turn.

Another well known solution involves the swinging of the stor- 1 Claim. (01. 178- 27) age members one at a time into the proximity of the armature-member, this again necessitating an armature member of sufficient size to cover the positions of all the storage members.

In said British patent there is disclosed an improved means of setting the storage members by traversing a frame carrying said members, past the armature in such a way thatone storage member is presented to the armature at a time and is then set in accordance with the positions taken up by the armature under the control of the next signal element received. It is therefore only necessary for the armature member to be large enough to act on one storage member at a time and thus the moment of inertia of the armature system can be reduced.

According to this last method when all the storage members have been set the indications have to be transferred to the translator mechanism after which the frame carrying the storage members has to be restored to its original position, and the storage members reset to normal before the first storage member can be presented to the armature for the reception of the first element of the next signal.

The object of the present invention is to provide improved means for setting the storage members in accordance with the received signal elements which will avoid the necessity of traversing the storage members while yet permitting the use of an armature member of minimum size, and to enable the maximum possible overlap in the timing of the several operations to be obtained. The storage members may be of the same general design as those disclosed in the abovementioned application, but they are not mounted in a traversing frame.

According to one feature of the present invention, a signal selector and storage mechanism for a printing telegraph receiver in which a striking member is caused to set a plurality of storage members one at a time, each such member being selectively set in accordance with the position of an armature member carrying said striking member, is characterised in this, that the striking member is of dimension no larger than would be necessary'to coact with one storage member only but is caused to coact with each storage member in turn by acting upon an intermediate member spanning the positions of all the said storage members, and that means is provided for causing said intermediate member to act selectively upon said storage member in turn. This intermediate member may consist of a light frame pivotally mounted on a fixed rod and able the spring l2; against a cam carried on the selector shaft i3. Five times in each revolution of the selector shaft 13 the cam activates striker lever 8 and drives the striker I outwards through the slot in the end 6 of arm the striker being withdrawn byspring |'2 as soon as the end H of striker lever 8 is dropped by the cam.

- The striker lever 8 is operated by the camwhile the arm 5 is held locked by the chopper lever I9 and the striker I is struck outwards through the slot in the turned over end 6 of arm 5, being immediately afterwards withdrawn to its normal position by the action of spring |2 as explained above. It canjnow be seen that the purpose of the chopper lever l9 (Fig. 1) is to ensure that the striker I is held correctly in the position corresponding to the last signal element received until the indication has been transferred to a storage member in a manner which. will now be described.

pivot pin 26 separated from one another by fric- 2 In Figure 2 the armature resetting mechanism tion washers (not shown) rigidly fixed to the pin and pressed together by a spring (not shown). The details and the action of the storage members are described in said British patent. According to the present invention however the pin 26 carrying the storage members is fixed and there is no traversing movement of the assembly of the storage members along the axis of the pin. A light frame 21 is suspended from a fixed rod 28 at points 29 and this light frame is traversed along rod 28 by the action of lever 30 mounted on a fixed pivot 3|, one end of lever 30 engaging the frame 21 near one of the suspension points 29, while the other end 32 is held against one end 33 of another lever 34 by the action of spring 35. Lever 34 is mounted on a fixed pivot 36 and its other end 31 is held against a cam mounted on the selector shaft |3 by means of spring 38. The shape of the cam co-operating with the end 31 of lever 34 is such that as the shaft |3 rotates the frame 21 is moved axially along shaft 28 from its extreme right-hand position as shown in the figure to its extreme lefthand position and is then immediately brought back to its extreme right hand position by the action of spring 35, this complete cycle occurring once for each revolution of shaft l3. It is to be noted that spring acts in opposition to spring 38. The tensions of these springs are so adjusted that spring 35 is not powerful enough to withdraw the end 31 of lever 34 from contact with the cam on selector shaft I3. Thus the light frame 21 is traversed in one direction by the action of spring 38 and in the return direction by,

spring 35 but if'owing to any mechanical defect the movement of frame 21 is impeded, no positive force exerted by the cam will be applied to the frame and cause mechanical damage. If frame 21 becomes accidentally held in some intermediateposition a gap will appear between the cooperating ends 32 and 33 of levers 30 and 34 respectively or the end 31 of lever 34 will remain outpf contact with the cam. Frame 21 is pro-' vided' witha projection 39 and as the frame is traversed this projection is brought in line in turn with-the upper arms of each of the storage members 25. In the storage member shown in the right, the upper arm 40 is designated. The lower .edge 4| of frame 21 is so positioned that it is directly opposite the end of the striker I when the armature of the receiving magnet is in one of its two operative positions and if the striker lever 8 is operated while the striker is in this position the lower edge 4| of frame 21 will be struck and the frame will be rotated through a limited angle around rod 28. Projection 39 will therefore strike the arm 40 of one of the storage members 25 and will rotate that storage member through an angle causing the long arm 42 of the storage'memberto be moved downwards. If the striker I is in its other possible position at the moment when striker lever 8 is operated the striker, although driven forward, will not strike the edge 4| of frame 21 and whichever storage member 25. is opposite projection 39 of frame 21 will not be struck and. will remain in its normal position. Frame 2! is restored to its normal po: sition immediately after each occasion upon which it is actuated by the striker by spring 43 acting on a restoring member 44 rotatably mounted on rod 28 at 45. The limit of travel of frame 21 as it returns to its normal position is determined by'a fixed/bar 46.

Thus, after five successive elements forming a completev codev combination have been received, some of the storage members 25 will usually have been struckzand others not, those which have been struck will have their long arms 42 depressed. When the five elements forming one combination have been received the traversing mechanism consisting of levers 30 and 34 restores the frame "to its original position ready for the next signal. 7

Meanwhile themechanism for transferring the stored signal combination to the translating mechanism comes into operation. This is sub stantially as described in said British patent. After the last 1 element of any code combination has been received, the shaft 48, on which the two arms 4| carrying the pivot pin 26 are rigidly fixed, is rotated through a limited angle. Only the further arm 41 is shown in Fig. 2, the corresponding second arm 41 supports the nearer end of pivot 26 and is omitted to simplify the drawing. This rotation of shaft 48 moves the storage members 25 away from the striking frame 21.,and towards the bell crank levers 49 which are themselves engaged with the vertical rods 50 (only one of which is shown) which actuate the translator mechanism as described in said British patent.

Shaft 48 is actuated by means of a member 5| rigidly fixed thereto and co-operating with a cam carried on the translator shaft 52 which moves; the forked ends 53, 54 of member 5|. When end 53 is raised, the five storage members 25 are moved towards the bell cranks 49 and the long arm 42 of each storage member engages either the upper or the lower of the corresponding pair of bell cranks 49 thus moving the associated vertical rod 50 into its limiting upper position or into its limiting lower position. As soon as the signal combination stored by the five storage members has been transferred to the five vertical rods, the forked end 54 of members 5| is actuatedby the cam on the translator shaft 48 and the arm 41, carrying the pin 26 on which the storage members are mounted, is brought back to its normal position. Immediately after the storage members have been brought back to their normal position they are reset to be ready for the next signal combination by means now to be described I A frame 55 is rotatably mounted on shaft 48 and has an arm 56 which continuously follows a cam on the translator shaft 52 in consequence of the tension of spring 5?. Once in each revolution of the translator shaft 52, just after the storage members have been broughtback to their normal position, a cam on the shaft 52 moves the arm 56 of frame 55 and rotates the frame 55 through a limited angle in a direction away from the frame 21. Frame 55 is thereby pressed against the lower extendin arms of the storage members 25 and any such members which were in the operated position, i. 'e., with their long arms depressed, are restored to their normal po-- sit-ions ready to be set by the next stroke of the striker I acting through projection 39 as has al ready been described.

From the foregoin description it can be seen that the operations involved from the moment of the commencement of the reception of any incoming signal combination till the complete coinbin'ation has been transferred to the translating mechanism are divided into" two distinct stages. Thus, the incoming signals actuate the receiving magnet armature and bring the striker 1 ,into position either to strike or miss the striking frame 2?. The striking frame 2! is traversed while the signal combination is being received and the projection 39 thereon ,is presented to each storage member in turn. The end of the first stage can be considered to be the moment when the last signal element has been received and the last storage member set. As soon as the last signal element has been received and the last storage member set, the striking frame 21 may be traversed back to its initial position, this movement taking place at tre same time as the assembly of storage members is being rocked forward to transfer the stored signal to the vertical rods 59. The fact that some of the restoring movements take place before the transfer of the signal combination to the translator mechanism is completed, leads to a valuable saving of time. permitting of greater reliability in operation and enabling operating speeds higher than previously obtainable.

As will have been realised from the foregoing description, the successful operation of the selector and storage mechanism is dependent on the correct timing of the successive movements by means of the various cams referredto and this will now be explained in greater detail.

Fig. 3 is a diagram which shows the contours and timing of the various cams and the operation of the mechanism described above can be readily understood by following the movements of the various parts.

In the figure, line A shows two complete received five element code combinations. eachpreceded by a start element (space) V and fol-- lowed with a stop element (mark). Thus, the first complete signal is represented by a start element (15 milliseconds) followed by mark, space, mark, space, mark each of about 15 milliseconds duration, and a stop element (shown as about 7 milliseconds). At this point the re-:

Line B"shows the cam contour operating the 70 c'eiv'er would be stopped and, as shown, imme-, diately restarted by the next start element the folarmature resetting lever I4 which operates six times for each signal combination. I

This-brings the armature 2 up against the receiving magnet 1 after the commencement of each received element and then releases it; if the magnet is energised the armature remains held by the magnet, if the element is of the other kind the armature is drawn away from the magnet as soon as the resetting lever H is released. t will be noticed that the resetting lever. 14 is not operated for the start element, indeedit could not be for the cam shaft I3 is at rest when this element is received. The normal rest condition of the transmission circuit is with mark current flowing and the connections are so atranged'that' the magnet l continues to be energised during the rest condition. Thus, the armature is held against the magnet after the stop element (mark) until the nextstart ele ment (space) releases it, whereupon it starts up the receiving mechanism. The resetting lever I4 is released, as stated above, While the element is still being received and the armature 2 is then either held against the magnet l or released according as to whether the magnet is energised or not. Shortly after the resetting lever 14 is released, the chopper lever I9 is operated by the cam contour shown in line C of the figure. This lever 19 locks the cam carrying the striker l in the position corresponding to the signal being received while the cam contour shown in line D operates to drive the striker forward and, as described above, to set the appropriate storage member 25. It will be noticed that the next movement of the resetting lever l4 (line B) commences before the chopper lever 19 is released. This movement of the resetting lever I4 commences to bring the armature 2 towards the receiving magnet l and the arm 5 carrying the striker I follows the armature under the action of the torsion spring [6 (Fig. 1) the moment the chopper lever l9 releases the arm 5.

Line E of Fig. 3 shows the contour of the camfwhich traverses the light frame 21 (Fig. 2) which transfers the indications given by the striker I to the appropriate storage members 25. The return traversing movement commences at the end of the fifth movement of the striker I and is completed during the next following start element when the cam shaft I3 is again in rotation'after' its pause.

Line F shows the cam on the selector shaft l3 which operates the clutch (not shown) to start the rotation of the translator shaft 52, which operation, as can be seen, takes place during the receipt of the fourth signal element. This shaft 52 carries the transfer cam indicated in line G, which operates to rock the frame 41 carrying the storage members 25 to transfer the stored signal combination to the bell cranks as engaging the five vertical rods 50, known as code bars which form the first part of the translator mechanism, which transfer operation. has been described above.

The transfer cam carried on shaft 52 operates approximately during the receipt of the stop element and immediately after the storage members 25 have set the code they are returned to their normal position whereupon said cam shown in line H operates to restore to their normal. position any of the storage members which have been depressed. I

'It can be seen that part of the return traverse movementof the light frame 27 (line E). and the transfer'from the storage members 25 to the code bars 50 (line G) and also the resetting to normal of the storage members (line H) can take place during the earlier part of the reception of the next ensuing signal combination.

This characteristic of the mechanism .Idescribed enables the various separate operations to be carried out in relatively deliberate manner, and, taken in conjunction with the advan age obtained by only requiring the armature li to actuate parts of minimum moment of inertia; it

permits of higher operating speeds in terms'f'of letters-per-minute without any of the moving parts of the mechanism being subjected to particularly exacting conditions and thus more" reliable operation is obtained.

What is claimed is:

A signal selector and storage mechanism for a printing telegraph receiver comprising a signal receiving electromagnet having a cooperating armature adapted to have two selective positions as determined by the successive code elements of a received signal, mechanical means for cyclically moving said armature from one of "said positions to the other, said means operating independent of a received signal, a plurality of storage members, one for each code element, each adapted to be set in response to a received signal code element, striking means, intermediate means disposed between said storage members and said striking means, said striking means adapted to selectively urge said intermediate means against said storage members under control of said mechanical means and said armature and means for traversing said intermediate means with respect to said storage members, said intermediate means adapted to act selectively upon said storage members in turn in response to received signal code elements. :1

REGINALD DENNIS SALMON. FREDERICK JAMES LESLIE TURNER.

REFERENCES CIT D UNITED STATES PATENTS Name Date Number Grifiith Oct. 31, 1933 

